Due to their cellular structure, the current location of a caller making a telephone connection with a mobile telephone is possible in the mobile telephone networks using the registers managed in the base stations of the networks, at least in the form of information about the cell in which the caller or the mobile telephone used for the call is located. Currently, however, an increase in Internet Protocol (IP) telephony is apparent. It must be assumed that IP telephony in the medium or long term will achieve a greater importance than conventional landline telephony to date in the public telephone network or PSTN (Public Switched Telephone Network) or even replace it. Up to now, DSL connections which are primarily used for IP telephony are mostly still coupled to analogue or ISDN landline connections. In this respect, a localization of callers who use the IP telephony is usually the case using the location information for the respective analogue or ISDN landline connection. It is also often the case that IP telephony providers exclude calls to emergency telephone numbers from the IP-based route using a corresponding configuration of the routers installed for their customers, and calls to these emergency numbers are made using the normal analogue or ISDN connection.
However, in the business area today, there are already a large number of IP connections provided with fixed IP address without associated landline connection; i.e. without associated ITU-T E.164 telephone number. With the increasing transition to IP telephony, an associated ITU-T E.164 location number for DSL broadband connections will therefore more and more frequently be dispensed with. The nomadic usage of IP telephony (also VoIP telephony) is also increasing where this is being used by means of VoIP capable end devices; for example WLAN capable mobile telephones. Mechanisms for localizing the initial point of an IP-based emergency call, however, do not engage for the nomadic usage of IP telephony and its use via broadband connections without associated landline connection.
In many countries to date, there are no final legal regulations for this type of usage with respect to the existing requirement for safety reasons for call localization for emergency calls. With the existing legal regulations, there is exclusive reliance on the assistance of the caller who should give the corresponding location information to the Public Safety Answering Point himself. However, under certain circumstances this can no longer be possible in a life-threatening situation or for a person with extreme health problems. On the other hand, however, technical solutions which completely solve the above mentioned problems pertaining to localizing the initial point of an IP-based emergency telephone call are basically not known to date.